Input Amplifier Offset Adjustments; Ac Convertor Frequency Response Adjustment - HP 3457A Service Manual

Calibration
5-15. Input Amplifier Offset Adjustment
5-16. This adjustment is not required unless the Self Test response is HARDWARE ERR and the AUXERR
message is 16. Adjust the Input Amplifier Offset as follows:
a, Remove all power from the 3457A (line cord and external inputs).
b. Loosen the two screws attaching the rear terminal assembly or terminal block assembly to the rear
panel and remove the terminal or terminal block assembly.
c. Turn the instrument upside-down and loosen the six captive screws in the bottom cover. (It Is not
necessary to remove these screws from the bottom cover).
d. Return the unit to an upright position and remove the top cover.
e. With the front panel of the instrument facing you, move the plug-in support assembly slightly to
the left to release the locking tab and lift the support assembly.
f, Lay the plug-in support assembly over the front panel to gain access to the Input Amplifier ad just-
ment (Vos Adj A2R113).
g. Reconnect power to the instrument and turn it ON.
h. Enable Diagnostic Routine number 4. (Press the Blue SHIFT key then the AUTO ZERO / D configuration
key. Use the | scroll key to display DIAGNOSTIC. Enter the number 4 and press the ENT key ).
i, Use an insulated adjustment tool to adjust A2-R113 (Vos adj) until the display reads PASSED.
j. Exit the Diagnostic Routine. (Press and hold the > / RESET display key until a tone is heard).
k. Turn the instrument OFF and remove the power cord.
I, Replace the plug-in support assembly, top cover and terminal or terminal block assembly.
m. Reconnect power and turn the instrument ON.
5-17. AC Convertor Frequency Response Adjustment
5-4
a. Remove all power from the 3457A (line cord and external inputs).
b. Loosen the two screws attaching the rear terminal assembly or terminal block assembly to the rear
panel and remove the terminal or terminal block assembly.
d. Return the unit to an upright position and remove the top cover.
e. With the front panel of the instrument facing you, move the plug-in support assembly slightly to
the left to release the locking tab and lift the support assembly.
3457A